A retrovirus designated human immuno-deficiency virus (HIV) is the causative agent of the complex disease termed Acquired Immune Deficiency Syndrome (AIDS), and is a member of the lentivirus family of retroviruses. M. A. Gonda, F. Wong-Staal, R. C. Gallo, "Sequence Homology and Morphological Similarity of HTLV III And Visna Virus, A Pathogenic Lentivirus", Science, 227, 173, (1985); P. Sonigo, N. Alizon, et al., "Nucleotide Sequence of the Visna Lentivirus: Relationship to the AIDS Virus", Cell, 42, 369, (1985). The complex disease AIDS includes progressive destruction of the immune system and degeneration of the central and peripheral nervous systems. The HIV virus was previously known or referred to as LAV, HTLV-III or ARV.
A common feature of retrovirus replication is the post-translational processing of precursor polyproteins by a virally encoded protease to generate mature viral proteins required for viral assembly and function. Interruption of this processing appears to prevent the production of normally infectious virus. Unprocessed structural proteins also have been observed in clones of non-infectious HIV strains isolated from human patients. The results suggest that the inhibition of HIV protease represents a viable method for the treatment or prevention of AIDS and/or the treatment or prevention of infection by HIV.
The HIV genome encodes structural protein precursors known as gag and pol, which are processed to afford the protease, reverse transcriptase and endonuclease/integrase. The protease further cleaves gag and gag-pol polyproteins to yield mature structural proteins of the virus core.
Considerable efforts are being directed toward the control of HIV by means of the structural protein precursors which are processed to yield the retroviral protease, reverse transcriptase and endonuclease/integrase. For example, a currently used therapeutic, AZT, is an inhibitor of the viral reverse transcriptase. H. Mitsuya, N. S. Broder, "Inhibition of the In Vitro Infectivity in Cytopathic Effects of HTLV III", Proc. Natl. Acad. Sci. USA, 83, 1911 (1986).
Research efforts have also been directed toward HIV protease inhibitors. For example, European Patent Application (EPA) 361 341; EPA 346 847; EPA 402 646; and EPA 337 714 all disclose compounds which are said to be useful as HIV protease inhibitors.
Unfortunately, many of the known HIV protease inhibitors suffer from toxicity problems, lack of bioavailability or short in vivo half-lives. In particular, it is believed that oral bioavailability is a necessary characteristic of an HIV protease inhibitor due to the chronic nature of the disease. However, peptides and peptide mimetics are notorious for their inability to be orally absorbed. Thus, despite the recognized therapeutic potential associated with a protease inhibitor and the research efforts expended thus far, a viable therapeutic agent has not yet emerged.
Accordingly, a primary object of the present invention is to provide novel HIV protease inhibitors which are useful in the treatment or prevention of HIV infection and/or the resulting acquired immune deficiency syndrome (AIDS).
A further object of the present invention is to provide therapeutic compositions that are of value in the treatment or prevention of HIV infection and/or the treatment or prevention of AIDS.
Still another object is to provide methods for the treatment or prevention of HIV infection and/or AIDS.
Other objects, features and advantages will become apparent to those skilled in the art from the following description and claims.